Question

We know that if the probability of an event happening is 100%, then the event is a certainty. Can it be concluded that if there is a 50% chance of contracting a communicable disease through contact with an infected person, there would be a 100% chance of contracting the disease if 2 contacts were made with the infected person

Answer 1

The correct answer to the following question will be "No". The further explanation is given below.

Explanation:

Probability (Keeping the disease out of 1 contact)

=
`0.5`

Probability (not keeping the disease out of 1 contact)

=
`1-0.5`

=
`0.5`

Now,

Probability (not keeping the disease out of 2 contact)

= Keeping the disease out of 1 contact × not keeping the disease out of 1 contact

On putting the estimated values, we get

=
`0.5* 0.5`

=
`0.25`

So that,

Probability (Keeping the disease out of 2 contact)

=
`1-0.25`

=
`0.75 \ i.e., 75 \ percent`

∴ Not 100%